battery cell

Abstract

The present invention relates to a battery cell (14) comprising a cell casing (26) in which a plurality of electrodes (20) are arranged. The cell casing has an opening (28) covered by a gas-permeable diaphragm (30), and the diaphragm (30) is covered from the outside by a cover element (34) that restricts the entry of substances into the cell casing (26).

Description

[Technical Field]

[0001] This invention relates to a battery cell. The battery cell has a cell casing on which a plurality of electrodes are arranged.

[0002] Increasingly, automobiles are driven, at least partially, by electric motors, thus configuring such vehicles as electric or hybrid vehicles. For powering electric motors, high-voltage batteries containing multiple individual battery modules are typically considered. The battery modules are often identical in structure to one another and are electrically connected in series and / or parallel to one another, so that the voltage applied to the high-voltage battery is several times the voltage provided by each individual battery module. Each battery module itself often has multiple battery cells located within a single common module casing, and these battery cells are electrically connected in series and / or parallel to one another.

[0003] Each battery cell typically has multiple galvanic elements. These galvanic elements each have two electrodes, namely an anode and a cathode, a separator placed between them, and an electrolyte with a freely movable charge carrier. For example, a liquid is used as such an electrolyte. Alternatively, battery cells can be formed as solid batteries, where the electrolyte exists as a solid. The anode and cathode, which form the electrodes of a battery cell, typically include a support that functions as a conductor. This conductor is usually fitted with an active material, which is a component of a layer deposited on the support, also called a conductor. In this case, the electrolyte may already be present in this layer, or it may be introduced later. However, at least the active material is suitable for absorbing working ions, such as lithium ions. Depending on its use as an anode or cathode, a different material is used for the support, and various types of layer materials are used.

[0004] To protect the galvanic elements, they are typically placed within a cell casing of the battery cell, often also called a cell cup. The cell casing also protects the electrolyte, and other components, from environmental influences. To ensure that each battery cell provides a relatively large capacity, several such galvanic elements, typically up to 100, are usually placed within a single common cell casing. To utilize existing space relatively efficiently and to simplify manufacturing, the individual components of the galvanic elements are planar and stacked vertically on each other in the stacking direction, thereby forming a substantially rectangular cell stack. In alternative embodiments, for example, the separator is configured in a strip with multiple electrodes on each of its opposing surfaces. This strip is rolled up to form a roll, particularly a so-called "jelly roll."

[0005] Depending on the arrangement of the galvanic elements, the cell casing is formed. In this case, the cell casing can be made rigid and, for example, manufactured from aluminum. In this case, the shape of the cell casing is, for example, a rectangular parallelepiped. Battery cells of this type are also called prismatic cells. In an alternative embodiment, the cell casing is made of a film that is covered around the galvanic elements. Battery cells of this type are also called so-called pouch cells.

[0006] During battery cell operation, i.e., charging and discharging, gases may be generated due to undesirable chemical reactions. This can lead to an increase in pressure within the cell casing, resulting in poor ion conductivity in some electrode areas, and consequently, power loss in the battery cell. On the other hand, the increased pressure can deform the cell casing, which can mechanically affect the area around the battery cell in particular. At relatively high pressures, the cell casing may rupture, causing electrolyte leakage and rendering the entire battery cell unusable. Undesirable chemical reactions may also occur between individual components of the battery cell and their surroundings.

[0007] To minimize such gas formation, special combinations of individual electrode and electrolyte materials are required, which increases manufacturing costs. On the other hand, selecting less reactive electrode materials often results in a reduction in capacity density and / or energy density. As an alternative, additional elements are provided, for example, within the cell casing to bind and / or react with the generated gases. However, these additional elements in the cell casing also increase the configuration space and weight of the battery cell, thus reducing energy density.

[0008] The fundamental problem underlying the present invention is to provide a particularly suitable battery cell that is advantageously improved in terms of operational reliability and / or energy density.

[0009] According to the present invention, this problem is solved by the feature of claim 1. Advantageous variations and configurations are the subject of the dependent claims.

[0010] The battery cell is configured to be rechargeable and is preferably a secondary battery. Preferably, the battery cell is, in a given state, a component of an automobile. The battery cell is suitable for this purpose and is specifically provided and tuned. In a given state, the battery cell is, for example, a component of an energy accumulator of an automobile, which has a plurality of battery cells of this type. Preferably, in this case, these battery cells are divided into a plurality of battery modules, which are also identical in structure to one another. The battery cells are, in particular, located within the casing of the energy accumulator or each battery module and are electrically connected to one another in parallel and / or in series. Thus, the voltage applied to the energy accumulator / battery module is several times the voltage provided by each of the battery cells. Preferably, in this case, all battery cells are identical in structure to one another, which facilitates manufacturing.

[0011] Therefore, the casings of the energy accumulator or each battery module, particularly those forming a composite of such battery cells, are preferably manufactured from metal, such as special steel or an aluminum alloy. For manufacturing, for example, die casting, deep drawing, casting press, or extrusion press are used. In particular, the casings of the energy accumulator or each battery module are configured to be closed. Preferably, an interface forming the terminals of the energy accumulator / battery module is installed inside the casing of the energy accumulator or each battery module. In this case, since the interface is in electrical contact with the battery cells, the supply of electrical energy and / or the extraction of electrical energy from the battery cells is possible from the outside of the energy accumulator, provided that appropriate connectors are plugged into the terminals.

[0012] The automobile is preferably a land vehicle, preferably having a certain number of wheels, of which at least one, and in appropriate forms multiple or all, wheels are driven by a single drive unit. In particular, one, preferably multiple, of the wheels are configured to be controllable. Thus, the automobile is able to move independently of a specific road, such as rails. In this case, the automobile can preferably be positioned substantially arbitrarily on a road, particularly one made of asphalt, coal tar, or concrete. The automobile is, for example, a commercial vehicle such as a freight car (Lkw: Lastkraftwagen) or a bus. However, particularly preferably, the automobile is a passenger car (Pkw: Personnkraftwagen).

[0013] The drive system preferably provides forward motion for the vehicle. For example, the drive system, particularly the main drive system, is at least partially electrically configured, and the vehicle is, for example, an electric vehicle. The electric motor is driven by an energy accumulator, which is, for example, configured as a high-voltage battery in a suitable form. The high-voltage battery preferably supplies a DC voltage, which is, for example, 200V to 800V, and for example substantially 400V. Preferably, an electrical converter is placed between the energy accumulator and the electric motor to adjust the power supply to the electric motor. Alternatively, the drive system has an additional internal combustion engine, thereby configuring the vehicle as a hybrid vehicle. Alternatively, the energy accumulator powers the vehicle's low-voltage onboard power grid, and the energy accumulator provides a DC voltage of 12V, 24V, or 48V in particular.

[0014] In further alternative forms, battery cells are components of industrial vehicles, industrial equipment, and handheld devices such as tools, particularly rechargeable screwdrivers. In even further alternative forms, battery cells are components of energy supply units, where they are used, for example, as so-called buffer batteries. In even further alternative forms, battery cells are components of portable devices, such as mobile phones or other wearable devices. Such battery cells can also be used in camping, model making, or other outdoor activities.

[0015] A battery cell has multiple electrodes, i.e., two or preferably more electrodes. In particular, these electrodes are divided into anodes and cathodes, in which case preferably half of these electrodes form the anode and the other half form the cathode. However, preferably there is one more anode than cathode. Particularly preferably, in this case all anodes and all cathodes are identical in structure to each other, which simplifies manufacturing. The electrodes are configured, for example, in a planar manner and have a support, also called a conductor. In particular, each support is formed of a metal foil, with one or both sides at least partially covered by a layer. For example, aluminum is used as the metal for the cathode support / conductor, and copper is used as the metal for the anode conductor.

[0016] In this case, the layers have a thickness of less than 1 mm. Preferably, the thickness of the support is less than 0.1 mm. Preferably, each layer has an active material, a binder and / or a conductive additive such as conductive carbon black. The active material is used to absorb / release working ions such as lithium ions, and is suitable, provided and prepared for this purpose. For the cathode, lithium metal oxides such as lithium cobalt(III) oxide (LiCoO2), NMC, e.g., NMC622 or NMC811, NCA, LNMO, or Li-rich materials are used as the active material. Alternatively, olivine such as LEP is used. For the anode, for example, graphite, Si-based materials or mixtures thereof, lithium metal, or LTO are used.

[0017] In particular, the electrodes are substantially rectangular. The electrodes are stacked, for example, one above the other to form a cell stack, in which case the stacking direction is perpendicular to the direction of extension of the electrodes which are arranged parallel to each other. In this case, the anodes and cathodes preferably appear alternately in the stacking direction of the cell stack. Preferably, one separator is placed between adjacent electrodes, that is, particularly between each anode and one cathode, and this separator is preferably similarly planar. For example, all separators are identical in structure to each other. In particular, these electrodes are stacked substantially flush with each other, in which case, for example, all anodes protrude at least slightly beyond the cathodes. Thus, based on the stacking of electrodes, the cell stack is also substantially rectangular.

[0018] In alternative embodiments, for example, all anodes, all cathodes, or separators are formed by a single common strip, or are attached to a single common strip. The strip itself is rolled up into a cylindrical shape, so that a so-called "jelly roll" is formed.

[0019] A battery cell has a cell casing in which electrodes, i.e., cell stacks or "jelly rolls," are arranged inside. In particular, the cell casing provides 0.1 dm 3 ~10dm 3 The volume is surrounded. For example, additionally, the cell casing is filled with electrolyte at least partially. The cell casing is preferably constructed rigidly. In other words, the battery cell is a prismatic cell in particular. In particular, the cell casing is made of a metal, for example, aluminum, i.e., pure aluminum or an aluminum alloy. The cell casing has, for example, a rectangular parallelepiped shape. Alternatively, the cell casing is constructed flexibly and is formed, for example, by a metal foil that is covered at least partially, particularly on one or both sides. The metal foil is wrapped around the electrodes, and the ends of the metal foil are preferably sealed so that the outflow of electrolyte and / or the inflow of ambient air into the cell casing is avoided.

[0020] The electrodes are positioned, in particular, directly within the cell casing, so that they are pressed against the inner wall of the cell casing, for example, directly or via another component, and thus stabilized by the inner wall. At the very least, the cell casing serves to directly protect the electrodes and / or to prevent contact between the electrodes / electrolyte and ambient air or other particles. In other words, since the electrodes inside the cell casing are preferably not surrounded, at least completely, by another component, the weight and material cost of the battery cell are reduced. In particular, there is no other casing surrounding the electrodes within the cell casing. Therefore, it is possible to fill the cell casing substantially entirely with electrodes and, optionally, with separators.

[0021] In a suitable form, the cell casing has at least one or two through-holes through which one terminal is guided. One or more terminals electrically contact at least some of the electrodes arranged in the cell casing, depending on the electrode wiring, thereby allowing the supply of electrical energy to and / or extraction of electrical energy from the galvanic element formed by the electrodes from outside the cell casing via one or more terminals. If only one terminal is provided, at least some of the electrodes are electrically contacted to the cell casing, thereby pre-setting the potential of the cell casing by these electrodes. In particular, one or more terminals are electrically insulated from the cell casing, and these terminals are fluid-tightly connected to the cell casing so that electrolyte leakage is avoided in the area of ​​the terminals.

[0022] The cell casing has an opening that is configured, for example, circular or rectangular. In particular, the area of ​​the opening is 50 μm². 2 ~15mm 2 Preferably 0.2 mm 2 ~3mm 2 The opening is covered by a gas-permeable diaphragm. In particular, the diaphragm is firmly bonded to the cell casing, so its movement relative to the cell casing is prevented. The diaphragm has a larger area than the opening, so it completely overlaps the opening. In particular, the area of ​​the diaphragm is smaller than the area of ​​the surface of the cell casing, which may have an opening. This reduces material costs.

[0023] Preferably, the diaphragm is bonded to the cell casing in a liquid-tight and / or gas-tight manner so that liquid and / or gas cannot pass through the space between the diaphragm and the cell casing to the opening. In this case, particularly preferably, the diaphragm is welded to the cell casing, in a suitable form, by a circumferential weld seam. Alternatively, for example, the diaphragm is bonded to the cell casing in a shape-connective and / or material-connective manner, particularly by adhesive. In this case, the opening is preferably completely surrounded by the adhesive or weld seam. For example, the bond is made directly adjacent to the opening, or a gap is formed between the opening and the bond of the diaphragm to the cell casing, e.g., the adhesive or weld seam. Thus, gas can only escape from or enter the cell casing through the opening, and the gas is also guided through the diaphragm.

[0024] In particular, the diaphragm is preferably selected to be permeable to at least CO, CO2, H2, and / or CH4. For example, the diaphragm does not block the passage of such gases at all, or only to a relatively small extent. However, the permeability of the diaphragm is relatively low with respect to moisture, especially water vapor. In particular, the ratio of the CO2 permeability to the moisture permeability of the diaphragm is at least 0.5, or at least 1, or at least 1.5. Preferably, this ratio is greater than 0.5 and less than 3. In short, the diaphragm is configured so that such gases generated in the cell casing can penetrate the diaphragm and reach the outside of the cell casing through the opening, which is utilized for this purpose. In this case, the diaphragm makes it difficult for moisture, especially water vapor, to enter the cell casing.

[0025] The diaphragm itself is covered by a cover element which is shifted from the outside, i.e., towards the outside with respect to the cell casing. In this case, at least the part of the diaphragm covering the opening is covered by the cover element. In particular, the opening is covered by the cover element. In this case, the cover element may be arranged inside the cell casing as well, but the cover element is shifted in the direction of the opening with respect to the diaphragm. Alternatively to this, the cover element is located outside the cell casing. For example, the cover element is in contact with the cell casing and / or the diaphragm or is spaced apart from one or both of them. In particular, the cover element is at least partially rigid. The cover element serves to limit the entry of substances into the cell casing, in particular moisture, especially water vapor, and is suitable and in particular provided and adjusted for this purpose. In this case, the entry of substances into the diaphragm is also preferably limited by the cover element. In other words, the cover element regulates, in particular, the amount and / or whether substances such as liquids or preferably gases flow into the cell casing through the diaphragm and the opening. Stated again differently, the cover element preferably closes the opening at least temporarily. At least, the cover element is preferably configured such that the gas flow through the diaphragm and the opening is limited or at least temporarily limited and thus regulated by this cover element. Preferably, the cover element is fluid-tight, for example, always or at least when in a predetermined state such as when the cover element is in a closed state. In other words, in this state, further flow of liquids, especially water, is preferably sufficiently excluded in principle and / or due to the structure. The cover element is preferably in a predetermined state as long as no gas is formed inside the cell casing.

[0026] Based on the opening and diaphragm, gas generated within the cell casing can escape, thereby avoiding the generation of excessive pressure within the cell casing that could cause damage to the electrodes and / or the cell casing. Thus, operational reliability is improved. For this purpose, only a diaphragm and cover element, which require a relatively small spatial volume, are needed. Furthermore, since the cover element can be placed outside the cell casing, it does not negatively affect the energy density. Based on the cover element, the diaphragm is protected at least partially from environmental influences from outside the cell casing, thus preventing damage to the diaphragm. In addition, in certain conditions in which the inflow and / or outflow of gas is completely blocked by the cover element, the cover element separates particles from the surrounding environment, for example, at least temporarily / partially, from the diaphragm. Thus, since the diaphragm is not loaded with liquid, especially water vapor, from outside the cell casing, liquid ingress is completely prevented, although the diaphragm's permeability to liquid remains, albeit reduced. In contrast, if the cover element allows for temporary gas leakage from the cell casing, water may enter the diaphragm during this period, but only in relatively small amounts, which are substantially contained by the diaphragm. Therefore, water ingress into the cell casing is almost completely prevented.

[0027] Diaphragms are manufactured from polymers, such as films, or polymer films. In a suitable form, the diaphragm is manufactured from or composed of PTFE, i.e., polytetrafluoroethylene. Preferably, the diaphragm has a crystallinity of 85% to 100% and a particle size of 0.2 g / cm³. 3 ~2g / cm 3has a density. When selecting such materials, gas permeability is provided. In this case, the diaphragm prevents or at least makes it difficult for moisture, particularly water vapor, to penetrate into the cell casing. In particular, as the diaphragm, the diaphragm described in International Publication No. 2012 / 079163 is used.

[0028] For example, the opening is arbitrarily positioned in the cell casing. However, particularly preferably, when the battery cell is configured as a pouch cell, the opening is located in a region near the conductor at one of the cylindrical ends, in a region where the foil that may exist is particularly sealed (for example, on the so-called gas pocket). In this case, the opening is preferably shifted inward from each end by up to 1 / 3 of the maximum length of the cell casing.

[0029] When the battery cell is a prismatic cell, preferably, the opening is particularly present in a region of an end face and / or a narrow-width face that is not parallel to the electrodes that may be stacked to form a cell stack. Alternatively, the opening is located on the side surface of the cell casing that is parallel to the electrodes, but preferably in the edge region, that is, shifted inward from the edge by up to 1 / 3 of the width of this side surface. Such a position of the opening simplifies the structure and does not require changing the existing design of the cell stack. Therefore, further, the opening is arranged in a region where the generated gas accumulates, thereby enabling relatively efficient discharge of the gas through the opening.

[0030] For example, the diaphragm is mounted on the outer surface of the cell casing. This provides a relatively large volume for the electrodes, as the diaphragm does not fill the internal space of the cell casing. Thus, a high capacity for the battery cell is still guaranteed. However, particularly preferably, the diaphragm is mounted on the inner wall of the cell casing. This prevents the diaphragm from excessively bulging outward, even when the internal pressure of the cell casing is relatively high, and based on the diaphragm's configuration, rapid gas flow is not possible. Thus, the diaphragm is stabilized by the inner wall, thereby increasing its robustness. Furthermore, the diaphragm is pressed against the inner wall under excessive pressure, thus preventing gas flow between the cell casing and the diaphragm. As a result, only gas outflow through the diaphragm is possible, and this is done in a controlled manner. In short, the diaphragm is located on the outward or inward-facing surface of the cell casing.

[0031] For example, the cover element is operated in a temperature-dependent manner. In this case, the cover element is preferably configured to completely block gas inflow and / or outflow at temperatures below a boundary value, thereby preventing fluid loading onto the diaphragm from outside the cell casing. Conversely, when the battery cell temperature is above the boundary value, the cover element is specifically adjusted so as not to block gas outflow from the cell casing. In other words, the diaphragm is open. However, as a result, moisture, especially water vapor, can reach the diaphragm from outside the cell casing.

[0032] In this case, the boundary value is preferably between 25 °C and 60 °C. Accordingly, based on such a boundary value, the cover element is adjusted such that gas can escape only when the battery cell is operating, i.e., only when electrical energy is supplied to and / or withdrawn from the battery cell. Only during this period can the generation of gas to be released occur. In contrast, when the battery cell is not required, the diaphragm is protected by the cover element.

[0033] Alternatively or in combination with this, the cover element is operated in response to the differential pressure between the pressure outside the cell casing and the pressure in the space formed between the cover element and the diaphragm. In particular, the volume of this space is less than 4 cm 3 less than, 1 cm 3 less than or 0.5 cm 3 less than. The pressure in the space between the cover element and the diaphragm is in particular the same as the pressure inside the cell casing or slightly lower than this based on the diaphragm.

[0034] The cover element is operated to allow, or at least facilitate, gas outflow from the cell casing, especially when the pressure in this space is greater than the pressure outside the cell casing, for example, by 0.1 bar, 0.5 bar, 1 bar, 2 bar, or 5 bar. Otherwise, the cover element is specifically closed, thereby completely preventing gas outflow. In this case, the diaphragm is also protected by the cover element from liquids coming from outside the cell casing. Thus, the protection of the diaphragm by the cover element is reduced only when the pressure on the side of the cover element facing the inside of the cell casing is higher compared to the pressure outside the cell casing. However, in this case, the direction of gas flow is directed outwards from the cell casing. Therefore, based on the direction of gas flow, the ingress of liquid to the diaphragm is prevented. As the differential pressure decreases, the gas velocity also decreases, which may allow the ingress of moisture, especially water vapor. However, in this case, the cover element is closed again, thereby similarly preventing the ingress of liquids.

[0035] For example, the cover element is a porous element or includes a porous element, in which case the pores are particularly open. For example, the porous element is foamed ceramic. The porous element increases the path length that the gas must travel, thereby increasing the resistance to gas leakage. Thus, the porous element limits gas leakage from the cell casing. In this case, the porous element also prevents the intrusion of moisture, especially water vapor, or at least makes it difficult, especially based on capillary action. For example, the porous element is configured to be completely liquid-impermeable and / or gas-impermeable in at least a certain area, for example on one side, thereby further increasing the distance that the gas and liquid must travel and thus the fluid-technical resistance. Thus, the side of the porous element opposite to the opening is configured such that the distance that the gas / liquid must travel is relatively longer due to the porous element. In particular, the porous element is approximately rectangular in shape, which facilitates its manufacture.

[0036] Particularly preferably, the cover element includes or is formed by a valve. This valve is operated using an actuator, such as a piezo actuator. This makes it possible to control the gas outflow from the cell casing, particularly depending on specific conditions, such as a differential pressure that may occur. Preferably, the cover element has a sensor, and the actuator is controlled depending on the sensor. Alternatively, the valve is, for example, spring-loaded and is configured particularly as a check valve. In this case, the valve is operated in response to the differential pressure between the pressure present outside the cell casing and the pressure in the space formed between the cover element and the diaphragm, i.e., when the pressure exceeds a predetermined boundary value. In this case, by changing the spring, it is possible to adapt to various different fields of use and / or other settings.

[0037] For example, the valve has a body that is impermeable to gases and liquids, for example, a diaphragm-shaped body. This body completely covers the opening or diaphragm when, for example, the cover element / valve is in a closed state. By longitudinal movement, particularly perpendicular to the extending direction of the body and / or diaphragm, the cover element is moved to an open state, and the body is preferably adequately supported. In this case, even when the cover element is open based on longitudinal movement, direct ingress of liquid into the opening is prevented. Alternatively, the cover element is configured in the form of a flap and is therefore pivotable with respect to and / or supported by the cell casing in particular. For example, in this case, the body, which may be present, is supported by the cell casing by bearings or, particularly preferably, film hinges. This simplifies the structure.

[0038] Alternatively, the cover element has a polymer layer directly bonded to a plastic, preferably another body such as a film. In this case, the polymer layer includes microstructures or nanostructures, i.e., structures having extensions of 100 μm to 1 nm. In particular, these structures are periodically repeated so that a pattern is formed. This facilitates manufacturing. The structures are, for example, flaps and / or grass-like members. If they are grass-like members, they are oriented particularly away from the inside of the cell casing, so that when the pressure outside the cell casing is increased or when liquid collides with the cell casing, these structures are pressed flat against the bottom of the polymer layer, thus the cover element is relatively densely constructed. Alternatively or in combination with this, the structures are adjustable, for example by applying a voltage, which allows or blocks the flow of gases and liquids. Microstructures or nanostructures improve mechanical robustness and reduce the required space.

[0039] In another alternative embodiment, the cover element has multiple cover wings, i.e., two, three, four, five, or more cover wings. Preferably, the number of cover wings is less than 10, thereby simplifying the structure. The cover wings are coupled to the cell casing, i.e., for example, directly attached to the cell casing or indirectly attached via another element. In this case, the cover wings are coupled to the cell casing at different locations from each other, i.e., at their respective coupling points, i.e., separated from each other. In particular, these coupling points surround the opening. In a suitable form, the cover wings are simply coupled on one side. The cover wings overlap at least partially with the diaphragm, i.e., the opening, or at least the portion of the diaphragm that covers the opening. Furthermore, the cover wings overlap each other. Reduced, each of the cover wings at least partially covers one or more of the other cover wings.

[0040] The cover vanes are flexibly constructed, meaning they are elastically deformable. In particular, the cover vanes are made of gas-impermeable and liquid-impermeable materials. Due to the flexible construction of the cover vanes, they can be bent, thereby releasing the diaphragm. In this case, the cover vanes stabilize each other, so unintended bending of one of the cover vanes does not cause the diaphragm to release. The force required for this is also relatively high. Furthermore, a relatively large creepage distance is provided based on their mutual overlap, so liquid intrusion between the cover vanes is substantially prevented from reaching the diaphragm, and in this case, gas outflow in the reverse direction is substantially prevented at the cover vanes that are pressed against the cell casing. However, bending of all or at least some of the cover vanes can release the diaphragm and, consequently, allow gas to escape.

[0041] Particularly preferable, the cover vanes are bonded to the outer surface of the cell casing so that the vanes do not press against the diaphragm, which could damage it. For example, the cover vanes are configured to bend when the pressure increases on the diaphragm side, thereby allowing gas to escape. Alternatively, the cover vanes are manufactured from two different materials that contract in different ways when the temperature rises. As the temperature rises, the cover vanes are curved, which in turn opens the diaphragm and, consequently, the opening.

[0042] Particularly preferable, the battery cell has a drying element to reduce moisture entering the cell casing through the opening. For this purpose, the drying element is suitable, specifically provided and tuned. Thus, moisture, such as water in liquid or gaseous form, that enters despite the cover element is bound by the drying element, preventing undesirable reactions with the electrodes and / or possibly the electrolyte placed within the casing. This further improves operational reliability. In particular, the drying element is configured such that water is bound by the drying element, and especially water molecules are absorbed.

[0043] For example, the drying element is positioned in the region of the opening, for example, surrounding the opening. In particular, the drying element has multiple silicon-containing groups bonded to the diaphragm. In other words, the diaphragm is functionalized with silicon-containing groups. Thus, the required space is reduced. Particularly preferably, the drying element is diaphragmatic, for example, loosely resting on the diaphragm or spaced apart from the diaphragm. Based on its position on the inner surface of the diaphragm, only the portion of liquid, especially water, that passes through the diaphragm into the interior of the cell casing is retained by the drying element. In other words, the diaphragm is used first to retain moisture / liquid, and only then is the drying element used. Thus, relatively long-term operation of the battery cell is possible without loss of function of the drying element.

[0044] For example, the diaphragm is formed to be crack-resistant. However, particularly preferably, the diaphragm is configured to crack when the differential pressure between the pressure outside the cell casing and the pressure inside the cell casing exceeds a boundary value. This avoids damage to the cell casing. For example, the diaphragm cracks completely and therefore breaks. Preferably, cracking occurs only when the boundary value is exceeded. When the differential pressure falls below the boundary value again, the cracking specifically ends. This avoids complete destruction of the diaphragm.

[0045] For example, a battery cell has multiple openings, each of which is covered by a correspondingly gas-permeable diaphragm, and each diaphragm is covered from the outside by a correspondingly positioned cover element to restrict the entry of moisture into the cell casing. For example, several or all of the openings are covered by the same cover element. In particular, in this case, all openings / diaphragms / cover elements are identical in structure to one another, differing only in their positions within the cell casing. Alternatively, for example, the cover elements and / or diaphragms are each configured differently, and therefore each cover element and / or diaphragm has different permeability and / or operates under different differential pressure or other conditions. Thus, flexibility is improved.

[0046] However, it is particularly preferable that the battery cell has only one opening, which simplifies manufacturing. Specifically, the diaphragm is in contact with the stabilizing element, at least in the area of ​​the opening, and is, for example, attached to the stabilizing element. In other words, the stabilizing element covers the opening at least partially. The stabilizing element is preferably constructed rigidly and is made of, for example, metal. Preferably, the stabilizing element is fixed to the cell casing, preferably by welding in a suitable form. The stabilizing element has another opening, each covered by the other opening. This allows for the selection of a relatively large opening, since the effective area available for gas outflow from the cell casing is limited to the sum of the other openings, in which case excessive gas outflow or liquid inflow into the cell casing will not occur.

[0047] In the appropriate configuration, the stabilization element is offset outward relative to the diaphragm. Thus, the maximum deformation of the diaphragm is defined by another opening, thereby stabilizing it. For example, the stabilization element is configured to rupture when the differential pressure between the pressure inside the casing and the pressure outside the cell casing increases. For this purpose, the stabilization element has, for example, one or more target rupture points, which are manufactured, for example, by laser or embossing. The differential pressure at which this occurs is, in this case, relatively precisely controllable. Alternatively, or in combination with this, the stabilization element is configured to rupture when a predetermined temperature is exceeded. Based on the rupture, the diaphragm is no longer stabilized and, consequently, overloaded, causing it to crack. As a result, a relatively large volume of gas can flow through the opening. In particular, the cover element in this case is also configured to rupture or at least allow gas outflow without substantially obstruction. Thus, controlled degassing of the battery cell is achieved, and uncontrolled failure of the cell casing due to excessive pressure is avoided. While the battery cells are indeed damaged and rendered unusable, the load on the surroundings is reduced. In other words, the diaphragm and stabilizing element act as a burst disc.

[0048] Alternatively or in combination with the embodiments described above, the cell casing has, in a suitable form, an incorporated target fracture site. The incorporated target fracture site is, for example, spatially separated from the opening, or, for example, the incorporated target fracture site has an opening. In another alternative embodiment, the target fracture site is formed by an opening. For example, the target fracture site has a surface of the cell casing where the wall thickness is reduced. Alternatively or in combination, the target fracture site has a surface of the cell casing with, for example, notches and / or grooves. In an advanced form, the target fracture site is an additional opening in the cell casing that is closed by a rupture disc. In other words, the cell casing has an additional opening that is completely closed by a rupture disc. In a suitable form, the target fracture site has an area of ​​0.01% to 50% of the area of ​​the cell casing. Preferably, the target fracture site has an area of ​​0.1% to 40%, particularly 0.3% to 30%, of the entire area of ​​the cell casing. For example, a diaphragm has an area that is 50% larger than the opening.

[0049] For example, the diaphragm is positioned on the inward-facing surface of the cell casing. In this case, for example, the diaphragm is not in complete physical contact with the cell casing outside the opening. In an alternative embodiment, the diaphragm is partially separated from the cell casing via a spacer.

[0050] In another alternative embodiment, the cell casing has, for example, an auxiliary opening, which is closed by a burst disc having an opening covered by a gas-permeable diaphragm. The burst disc is formed, for example, by reducing the wall thickness of the cell casing, or is initially a separate component from the cell casing and attached to the cell casing for assembly. In particular, the burst disc forms a target rupture site, if any. Preferably, the diaphragm is attached to the outward-facing surface of the burst disc. In this case, for example, from the outside, the diaphragm is pressed against another, or possibly present, stabilizing element, which has a plurality of additional openings. Preferably, in this case, the stabilizing element is attached to the burst disc. In an alternative embodiment, the diaphragm is positioned on the inward-facing surface of the burst disc, and the diaphragm is supported on a partial surface of the burst disc via a spacer.

[0051] The present invention further relates to a composite of such battery cells, the composite being preferably a battery module or a high-voltage battery. Furthermore, the present invention relates to an automobile, such as a passenger car (PKW), equipped with such a type of battery cell, and in particular a composite of such a type. The battery cell is used, in particular, for supplying power to the main drive system of the automobile.

[0052] The advantages and developmental forms described for battery cells can be appropriately applied to composites / automobiles, as well as to each other, and vice versa.

[0053] Embodiments of the present invention will be described in detail below with reference to the drawings. [Brief explanation of the drawing]

[0054] [Figure 1] This is a schematic diagram showing an automobile having multiple battery cells of the same structure. [Figure 2] This is a schematic cross-sectional view of one of the battery cells having a cell casing. [Figure 3] This diagram schematically shows a portion of a cell casing having an opening for gas outflow, in which case the opening is covered by a gas-permeable diaphragm, which is covered from the outside by a cover element to restrict gas outflow from the cell casing. [Figure 4] This figure corresponds to Figure 3, showing the case where the pressure inside the cell casing is different. [Figure 5] This figure corresponds to Figure 3, showing a different pressure within the cell casing. [Figure 6] This figure corresponds to Figure 3, showing a different pressure within the cell casing. [Figure 7] This diagram schematically illustrates an alternative embodiment of a battery cell. [Figure 8] This diagram schematically illustrates an alternative embodiment of a battery cell. [Figure 9] This is a plan view showing an alternative embodiment of the stabilization element. [Figure 10] This is a plan view showing an alternative embodiment of the stabilization element. [Figure 11] This diagram schematically illustrates an alternative embodiment of a battery cell. [Figure 12] This diagram schematically illustrates an alternative embodiment of a battery cell. [Figure 13] This diagram schematically illustrates an alternative embodiment of a battery cell. [Figure 14] This diagram schematically shows an alternative embodiment of the cover element. [Figure 15] This diagram schematically shows an alternative embodiment of the cover element. [Figure 16] This diagram schematically shows an alternative embodiment of the cover element. [Figure 17] This diagram schematically shows an alternative embodiment of the cover element.

[0055] Corresponding parts are denoted by the same reference numeral in all drawings.

[0056] Figure 1 schematically shows an automobile 2 in the form of a passenger car (PkW). The automobile 2 has multiple wheels 4, at least some of which are driven by a drive unit 6 including an electric motor. Thus the automobile 2 is an electric vehicle or a hybrid vehicle. The drive unit 6 has a converter that supplies power to the electric motor. The converter of the drive unit 6 is also powered by an energy accumulator 8 in the form of a high-voltage battery. For this purpose, the drive unit 6 is connected to an interface 10 of the energy accumulator 8, which is inserted into an energy accumulator casing 12 made of special steel.

[0057] Inside the energy accumulator casing 12 of the energy accumulator 8 are several battery modules (not shown in detail) of the same structure, each containing several battery cells 14. In this case, the battery cells 14 of each battery module are connected to each other, partially in series and partially in parallel. The battery modules are also connected to each other, both in series and / or in parallel. The electrical complex of the battery modules is electrically connected to the interface 10, which allows for the discharge or charging (regeneration) of the battery modules and, consequently, the battery cells 14, when the drive unit 6 is in operation. In this case, based on the electrical connection, the 400V voltage provided by the interface 10 is several times the voltage provided by each battery module and each battery cell 14.

[0058] Figure 2 shows a cross-sectional view of one of the battery cells 14, which are all identical in structure. The battery cell 14 has multiple anodes 16 and cathodes 18, of which only two are shown. The anodes 16 and cathodes 18 that form the electrodes 20 of the battery cell 14 are each planar in shape and are stacked alternately to form a cell stack, in which case a separator, not shown in detail, is placed between each adjacent anode 16 and cathode 18. The anodes 16 protrude beyond the cathodes 18 on one common side, that is, each constitutes a conductor formed by the respective metal sheets. In this case, in the region of the protrusion, each conductor is free from other components, but in the other region, each conductor, also called a support, is coated with a layer containing active material. The cathodes 18 also protrude similarly beyond the anodes 16, in which case the protrusions are located on opposite sides of the stack formed by the anodes 16 and cathodes 18.

[0059] The protrusions of the anode 16 and cathode 18 are welded to busbars 22 (tabs) made of copper, respectively. In this case, the anode 16 and cathode 18 are each assigned one common busbar 22. Each busbar 22 has one terminal 24, which is guided through the cell casing 26 in which the anode 16 and cathode 18 are located. In other words, electrodes 20 are located inside the cell casing 26. The cell casing 26 is rigidly constructed and made of aluminum, i.e., an aluminum-containing material. Thus, the battery cell 14 is a prismatic cell. The cell casing 26 is filled with a liquid electrolyte, which is not shown in detail.

[0060] Figures 3 to 6 show a schematic partial cross-sectional view of a battery cell 14 in operation. The cell casing 26 has an area of ​​50 mm². 2It has an opening 28. In this case, the opening 28 is located in the same wall of the cell casing 26, which also has a through-hole for one of the terminals 24. Except for the opening 28, the cell casing 26 is configured to be liquid-tight and gas-tight. Therefore, the area between the terminal 24 and the through-hole of the cell casing 26, which is positioned corresponding to this terminal, is filled with plastic, which is not shown in detail.

[0061] The opening 28 is covered by a gas-permeable diaphragm 30, which is fixed to the inner wall 32 of the cell casing 26 having the opening 28, specifically by welding or adhesive. In the illustrated example, the diaphragm 30 covers the entire inner wall 32 of the casing 26, and thus completely covers the opening 28. The diaphragm 30 is made of PTFE, at least in part. Therefore, gases such as H2, CO, CH4, and CO2 can pass through the diaphragm 30 relatively easily, while the passage of moisture, especially water vapor, and other liquids is comparatively more difficult. The portion of the diaphragm 30 that covers the opening 28 is covered on the outside with respect to the cell casing 26 by a cover element 34. The cover element 34 is located on the outer surface of the cell casing 26 and is attached to the cell casing. The cover element 34 is gas-tight and liquid-tight and functions to restrict the inflow of gas into the cell casing 26. Therefore, the cover element 34 completely prevents moisture from the surroundings, especially water vapor, from entering the opening 28 and, consequently, the diaphragm 30.

[0062] During operation of the battery cell 14, gases 36 such as H2, CO, CH4, and / or CO2 may form inside the cell casing 26 due to, for example, a relatively high load or an undesirable chemical reaction based on undesirable foreign particles. In this case, since the gas 36 requires a larger volume than the reacting material, the pressure inside the cell casing 26 increases. As shown in Figure 4, the gas 36 may flow through the diaphragm 30 to the opening 28, that is, into the space 38 formed between the cover element 34 and the diaphragm 30, which in this embodiment is defined by the opening 28.

[0063] When the pressure difference between the outside of the cell casing 26 and the pressure inside the space 38 exceeds a threshold value, for example, 0.5 bar, the cover element 34 is operated, thereby partially opening. Thus, gas flows out from the space 38 to the surroundings of the cell casing 26, as shown in Figure 5. Another gas 36 also flows out from the inside of the cell casing 26 to the surroundings through the diaphragm 30 and the opening 28. In this case, the diaphragm 30 prevents moisture from entering the cell casing 26 (see also below).

[0064] Since the gas 36 has been released at least partially, when the pressure difference between the pressure inside the space 38 and the pressure outside the cell casing 26 drops again, the cover element 34 closes again, as shown in Figure 6, so that no further leakage of gas 36 from the space 38 and, consequently, from the cell casing 26 occurs. Therefore, from thereafter, the diaphragm 30 is again completely covered by the cover element 34, preventing moisture from entering the opening 28.

[0065] Based on the structure of the battery cell 14, the entry of moisture into the electrodes 20 from the outside of the battery cell 26 is only possible if the cover element 34 is operated to allow gas flow. However, in this case, since the gas 36 flows from the inside to the outside of the cell casing 26, the intrusion of moisture is prevented or at least significantly reduced based on the flow motion of the gas 36.

[0066] In an alternative embodiment, the operation of the cover element 34 is additionally or alternatively dependent on the temperature of the battery cell 14. In this case, when the temperature of the battery cell 14 exceeds a threshold value, for example 40°C, the cover element 34 is operated, thereby allowing the gas 36 to escape.

[0067] The diaphragm 30 is further configured to rupture if the pressure difference between the pressure outside the cell casing 26 and the pressure inside the cell casing 26 exceeds another higher threshold value. This threshold value, i.e., the other threshold value, is 10% to 25% lower than the maximum pressure load on the cell casing 26, i.e., the pressure difference at which irreversible failure of the cell casing 26 occurs. This other threshold value is, in particular, 6 bar to 8 bar. In other words, the diaphragm 30 acts as a burst diaphragm that ruptures to avoid failure of the cell casing 26.

[0068] In other words, when a relatively large volume of gas 36 is formed, this gas enters the space 38, thereby operating the cover element 34. As a result, the pressure in the space 38 is substantially equivalent to the pressure around the cell casing 26, i.e., the pressure outside the cell casing 26. When the differential pressure between the pressure in the space 38 and the pressure inside the cell casing 26 exceeds another threshold value, the diaphragm 30 ruptures under control, and as a result, the escape of gas 36 from the inside of the cell casing 26 to the outside is accelerated, based on the fact that the fluid-technical resistance of the diaphragm 30 is eliminated or reduced. Thus, damage to the casing 26 due to excessive pressure inside the cell casing 26 is avoided.

[0069] When the differential pressure falls below another threshold value, the rupture of the diaphragm 30 stops. Most of the gas 36 escapes, and even if the differential pressure between the area around the cell casing 26 and the space 38 falls below the threshold value of 0.5 bar, the cover element 34 is operated again, so that the opening 28 is completely covered by the cover element. Thus, the intrusion of moisture into the cell casing 26 is again prevented by the cover element 34. Thus, further operation of the battery cell 14 is possible, but based on the rupture of the diaphragm 30, the intrusion of liquid becomes possible, at least temporarily and partially.

[0070] Figure 7 shows a modified form of the battery cell 14 shown in Figure 3. In this embodiment, the battery cell 14 has a drying element 40. The drying element 40 consists of silicon-containing groups and is provided as a layer, and this layer covers the diaphragm 30 planarly on the inside, that is, completely in this embodiment. In other words, the drying element 40 exists as a layer separate from the diaphragm 30. The drying element 40 does not obstruct the passage of gas 36 at all or only slightly. However, moisture, i.e., water (vapor), that still reaches through the opening 28 and the diaphragm 30 is bound and / or absorbed by the drying element 40 and therefore cannot reach the electrodes 30 and / or electrolyte. Thus, the drying element 40 helps to reduce moisture entering the cell casing 26 through the opening 28.

[0071] Figure 8 shows another variant of the battery cell 14 shown in Figure 3. In this embodiment, the opening 28 is covered on its outer surface by a diaphragm 30, which is fixed to the outer surface of the cell casing 26, specifically by welding or adhesive. Furthermore, the battery cell 14 has a stabilization element 42 made of metal. The stabilization element 42 is planar and is entirely pressed against the diaphragm 30. Thus, the diaphragm 30 is also pressed against the stabilization element 42 in the area of ​​the opening 28. In this case, the diaphragm 30 is positioned between the cell casing 26 and the stabilization element 42, and therefore the stabilization element is offset outward with respect to the diaphragm 30.

[0072] Figures 9 and 10 show, in plan view, embodiments of the stabilizing element 42. Each embodiment has a plurality of other openings 44. In the embodiment shown in Figure 9, each of the other openings 44 is provided by circular notches, separately from each other. In the embodiment shown in Figure 10, the other openings 44 are strip-shaped.

[0073] Another opening 44 or at least a portion of each of the other openings is positioned above the opening 28, and thus the other opening is covered by the opening 28. The stabilizing element 42, and by extension the diaphragm 30, is also completely covered by a cover element 34 positioned on the outside of the cell casing 26. When the pressure inside the cell casing 26 rises and the cover element 34 opens at least partially, the diaphragm 30 bulges slightly outward only in the area of ​​the other opening 44, thereby preventing excessive deformation of the diaphragm 30. The stabilizing element 42 ruptures only when the differential pressure between the inside of the cell casing 26 and the outside of the cell casing 26 exceeds another boundary value, namely 6 bar to 8 bar, so that the stabilizing element 42 no longer stabilizes the diaphragm 30, and therefore the diaphragm ruptures, thereby allowing a relatively large volume of gas 36 to escape without obstruction.

[0074] Figure 11 shows a plan view of the cover element 34. The cover element 34 has a plurality of cover vanes 46, each of which is coupled, i.e., attached to the cell casing 26 at coupling points 48 spaced apart from each other. The coupling points 48 surround the opening 28, and the cover vanes 46 are positioned to cover at least partially each other at the ends opposite each coupling point 48, and also cover the opening 28, and therefore the diaphragm 30. The cover vanes 46 are flexibly constructed and are made of, for example, a polymer. When the differential pressure exceeds a boundary value, the pressure is increased, causing the cover vanes 46 to be lifted at their free ends spaced apart from each coupling point 48, or otherwise from the cell casing 26 to which these cover vanes are in planar contact, thereby allowing gas to escape. In contrast, when the differential pressure is relatively small, gas leakage from the inside of the cell casing 26 and / or moisture ingress from the outside of the cell casing 26 into the opening 28 or at least into the diaphragm 30 are prevented based on the relatively large creepage distance provided by the overlap. In an alternative embodiment, the cover vane 46 is manufactured from two different materials having different temperature characteristics. In this case, the material of the portion of the cover vane 46 facing the outside of the cell casing 26 is selected so that the cover vane contracts strongly when the temperature rises. As a result, at high temperatures, the cover vane 46 deforms so that the opening 28, and thus the diaphragm 30, is released.

[0075] Figure 12 again shows the battery cell 14 partially in a schematic cross-sectional view. In this embodiment, the opening 28 is again covered from the outside by the diaphragm 30. The diaphragm 30 is also completely covered by a cover element 34, which includes a porous element 50, i.e., a foamed ceramic or foamed material. The porous element 50 has several open pores, which are not shown in detail. Gas flow is possible through these pores, in this case, and is limited by increased fluid-technical resistance.

[0076] On the side opposite the diaphragm 30, the rectangular porous element 50 is provided with a layer 52 that is completely fluid-tight. This layer 52 ensures that the outflowing gas 36 takes a relatively long path through the porous element 50 to escape, and in this case, the size of the cover element 34 does not become excessively large. Similarly, the layer 52 ensures that the impacting water also reaches the opening 28 only after taking a relatively long path through the porous element 50, which is delayed relatively significantly based on capillary action.

[0077] Figure 13 shows another configuration of the battery cell 14 according to Figure 12. In this case as well, the diaphragm 30 is located on the outer surface of the cell casing 26 and covers the opening 28. A cover element 34 is also located on the outer surface of the casing 26. The cover element 34 has a valve 54, which in the illustrated embodiment is formed by a valve. The valve 54 has a fluid-impermeable body 56, which is molded such that when the body 56 abuts the cell casing 26 at its edge, the body completely surrounds the diaphragm 30. The body 56 is made of plastic and is supported by guides (not shown in detail) so as to be longitudinally movable perpendicular to the surface of the diaphragm 30. The body is further supported by a stopper 58 by a plurality of springs 60, in which case the body 56 is located between the stopper 58 and the diaphragm 30. The spring 60 is configured such that, as long as the pressure difference between the pressure inside the casing 26 and the surrounding area of ​​the cell casing 26 is less than a threshold value of 0.5 bar, the body 56 is pressed against the diaphragm 30 and the cell casing 26 by the spring. When this threshold value is exceeded, based on the pressure, the body 56 is separated from the diaphragm 30 against the force applied by the spring 60, thereby allowing the gas 36 to escape.

[0078] In embodiments not shown in detail, the spring 60 is replaced by an actuator, or an actuator is provided in addition. The actuator, such as a piezo actuator or a magnetic element, is operated to separate the main body 56 from the diaphragm 30 when a predetermined condition occurs, such as a predetermined temperature rise.

[0079] Figure 14 shows an alternative embodiment of the valve 54. In this embodiment, the body 56 is pivotably supported by a hinge 62, for example, a film hinge, on another component of the cover element 34 or the cell casing 26. In one embodiment, the valve 54 is configured as a check valve, so that liquid contacting the body 56 from the outside closes the valve 54. In embodiments not shown in detail, the body 56 is further loaded by a spring 60 not shown in detail, which pushes or pulls the body 56 to a closed position when the differential pressure is less than a boundary value. In another embodiment not shown, the body 56 is additionally or alternatively operated by an actuator.

[0080] Figures 15 and 16 show variations of the cover element 34. In alternative embodiments, the polymer layer 64 is attached to a separate component, or the polymer layer 64 forms another diaphragm. The polymer layer 64 has a base 66 to which a plurality of nanostructures 68 are attached. Each of these nanostructures 68 is arranged in a repeating pattern with a spacing of 200 nm between them. Each nanostructure 68 has a pin 70 attached to the base 66 and facing away from the base, to which a thickened portion 72 is bonded at the free end opposite the base 66. The dimensions of the thickened portion 72 depend on the applied voltage. In the normal state of the cover element 34, i.e., when no voltage is applied, the thickened portions 72 bulge so that adjacent thickened portions 72 are in contact with each other, thereby preventing the passage of gas 36, as shown in Figure 15. When a voltage is applied, the thickened portion 72 contracts, causing adjacent thickened portions 72 to be separated from each other. As a result, gas 36 can flow through, as shown in Figure 16.

[0081] Figure 17 shows a variation of the cover element 34, similarly formed by a polymer layer 64. However, in this case, the nanostructure 68 is configured as a fine, grass-like member. In other words, only individual pins 70 protrude from the bottom 66, and these pins are configured to be relatively flexible. In this case, as in the embodiments described above, the pins 70 are oriented away from or outward from the cell casing 26. When a droplet collides from the outside, the pins 70 are bent toward the bottom surface 66, causing the pins 70 to overlap and contact each other. As a result, the passage of moisture is blocked. As soon as the moisture is removed, the pins 70 substantially return to their original positions. Flow of gas 36 in the reverse direction is always possible at the straight-oriented pins 70.

[0082] In embodiments not shown in detail, the shape of the pins 70 is altered, such that these pins are shortened and / or configured conically. In embodiments not shown in detail, the pins 70 are enlarged, so that the polymer layer 64 has microstructures instead of nanostructures 68. In other words, the size and spacing of the pins 70 are enlarged. However, the shape of the pins 70 remains substantially unchanged.

[0083] The present invention is not limited to the embodiments described above. Rather, those skilled in the art can derive other aspects of the present invention from these embodiments without departing from the scope of the invention. Furthermore, all the individual features described in particular in relation to the individual embodiments can be combined with each other in other ways without departing from the scope of the invention. [Explanation of Symbols]

[0084] 2. Automobile 4 wheels 6. Drive unit 8. Energy Accumulator 10 Interfaces 12 Energy Accumulator Casing 14 battery cells 16 Anodes 18 Cathode 20 electrodes 22 Bus Bar 24 terminals 26 Cell casing 28 Aperture 30 diaphragms 32 Inner wall 34 Cover Element 36 Gas 38 Space 40 Drying element 42 Stabilizing element 44 Another opening 46 Cover Wing 48 Connection point 50 Porous Elements 52 layers 54 valves 56 Main unit 58 Stopper 60 springs 62 Hinge 64 Polymer layer 66 Bottom 68 Nanostructures 70 pins 72 Thick part

Claims

1. A battery cell (14) comprising a cell casing (26), wherein a plurality of electrodes (20) are arranged within the cell casing, the cell casing having an opening (28) covered by a gas-permeable diaphragm (30), the diaphragm (30) being covered from the outside by a cover element (34) for restricting the entry of substances into the cell casing (26), The cover element (34) has a plurality of flexible cover wings (46) that overlap each other and at least partially with the diaphragm (30), and the cover wings are spaced apart from each other and coupled to the cell casing (26). Battery cell (14).

2. The battery cell (14) according to claim 1, wherein the diaphragm (30) is attached to the inner wall (32) of the cell casing (26).

3. The battery cell (14) according to claim 1 or 2, wherein the cover element (34) is operated in response to the differential pressure between the pressure outside the cell casing (26) and the pressure in the space (38) formed between the cover element (34) and the diaphragm (30).

4. The battery cell (14) according to claim 1 or 2, wherein the cover element (34) has a valve (54).

5. The battery cell (14) according to claim 1 or 2, wherein the cover element (34) has a polymer layer (64) containing a microstructure or nanostructure (68).

6. The battery cell (14) according to claim 1 or 2, further comprising a drying element (40) for reducing moisture entering the cell casing (26) through the opening (28).

7. The battery cell (14) according to claim 6, wherein the diaphragm (30) is covered in a planar manner on the inside by the drying element (40).

8. The battery cell (14) according to claim 1 or 2, wherein the diaphragm (30) is configured to rupture when the differential pressure between the pressure outside the cell casing (26) and the pressure inside the cell casing (26) exceeds a boundary value.

9. The battery cell (14) according to claim 1 or 2, wherein the diaphragm (30) is pressed against a stabilizing element (42) in the region of the opening (28), and the stabilizing element has a plurality of other openings (44), each of which is covered by the opening (28).

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